The subject matter disclosed herein relates to heating systems. More specifically, the subject disclosure relates to burners for residential and commercial heating systems.
Heating systems, in particular furnaces, include one or more burners for combusting a fuel such as natural gas. Hot flue gas from the combustion of the fuel proceeds from the burner and through a heat exchanger. The hot flue gas transfers thermal energy to the heat exchanger, from which the thermal energy is then dissipated by a flow of air driven across the heat exchanger by, for example, a blower.
A typical prior art construction is shown in FIG. 1. A burner 100 is located external to a heat exchanger 102. The burner 100, often referred to as an inshot burner 100, receives a flow of fuel from a fuel source 104. An ignition source 106 combusts the flow of fuel to create a combustion flame 110.
Another type of burner is a premix burner in which fuel and air are mixed in a burner inlet tube prior to injection into a combustion zone 112 where the ignition source 106 ignites the mixture. Premix burners, compared to inshot burners, typically emit much lower levels of NOx, the emissions of which are tightly regulated and restricted by many jurisdictions. Because of this advantage of premix burners, it may be desirable to utilize premix burners in furnaces.
In multi-burner applications such as furnaces, each heat exchanger is supplied with hot combustion products by individual burners. Typically only one burner contains an igniter and upon ignition, the remaining burners are lit form the single burner with the igniter. Flame carryover is the ability to transfer the flame from one burner to the next. For in-shot burner applications, a small channel is formed by the top and bottom plates between adjacent burners such that a small flame transfers hot gases to light each successive burner. Because premix burners are fabricated individually and not by adjoining plates, the carryover between adjacent burners must be achieved in another way. In addition, there is a need to optimize the carryover path so that a sufficient amount of hot gas is transferred to light an adjacent burner without affecting the heating efficiency of the furnace.